As an antialiasing technique for improving the viewability of characters on a liquid crystal display device, a technique (subpixel rendering) is currently under development which produces an antialiasing effect not at a pixel level but at a subpixel level by displaying different tones in a plurality of subpixels of each of those pixels falling on a character edge.
FIG. 14 is a schematic view showing the case of a standard display of a character line on a liquid crystal display device (three-color liquid crystal display device) having pixels each constituted by three subpixels, namely an R (red), a G (green), and a B (blue) subpixels. FIG. 15 is a schematic view of the case of a display of a subpixel rendered character line on the three-color liquid crystal display device. It should be noted that each subpixel takes on any one (8-bit data) of tones of 0 to 255, and the R, G, and B subpixels are abbreviated as “RSP”, “GSP”, and “BSP”, respectively, as needed.
As shown in FIGS. 14 and 15, whereas RSP=255, GSP=255, and BSP=255 in each of the pixels P1 to P3 in FIG. 14, RSP=255, GSP=255, and BSP=0 in each of the pixels P1 to P3 in FIG. 15. Further, whereas RSP=255, GSP=255, and BSP=255 in each of the pixels P4 to P6 in FIG. 14, RSP=0, GSP=255, and BSP=0 in each of the pixels P4 to P6 in FIG. 15. This shows that an antialiasing effect is produced at a subpixel level in FIG. 15.
Meanwhile, with an aim to enhance the luminance of each pixel, a liquid crystal display device (multi-color liquid crystal display device is also currently under development which has pixels each constituted by subpixels of four or more different colors.
FIG. 16 is a schematic view showing the case of a standard display of a character line on a four-color liquid crystal display device having matrix arrangements of four subpixels, namely an R (red), a G (green), a B (blue), and a white (W) subpixels. It should be noted here that for a display on the four-color liquid crystal display device of RGB data premised on a three-color liquid crystal display device, RGBW data is created from the RGB data in the manner shown in FIG. 17. That is, in a case where it is specified in the RGB data that RSP=TX, GSP=TY, and BSP=TZ, such tones are specified in the RGBW data that RSP=j×TX−(smallest value among the tones TX to TZ), GSP=j×TY−(smallest value among the tones TX to TZ), BSP=j×TZ−(smallest value among the tones TX to TZ), and WSP=smallest value among the tones TX to TZ (where 1≦j≦2).
For example, in a case where it is specified in the RGB data that RSP=0, GSP=0, and BSP=0, it is specified in the RGBW data that RSP=1×0−(0)=0, GSP=1×0−(0)=0, BSP=1×0−(0)=0, and WSP=0. Alternatively, in a case where it is specified in the RGB data that RSP=255, GSP=255, and BSP=0, it is specified in the RGBW data that RSP=1×255−(0)=255, GSP=1×255−(0)=255, BSP=1×0−(0)=0, and WSP=0. Alternatively, in a case where it is specified in the RGB data that RSP=0, GSP=255, and BSP=255, it is specified in the RGBW data that RSP=1×0−(0)=0, GSP=1×255−(0)=255, BSP=1×255−(0)=255, and WSP=0.
FIG. 18 is a schematic view showing the case of a standard display of a character line on a four-color liquid crystal display device having stripe arrangements of four subpixels, namely an R (red), a G (green), a B (blue), and a white (W) subpixels. It should be noted here that for a display on the four-color liquid crystal display device of RGB data premised on a three-color liquid crystal display device, RGBW data is created from the RGB data in the manner shown in FIG. 19. That is, in a case where it is specified in the RGB data that RSP=TX, GSP=TY, and BSP=TZ, such tones are specified in the RGBW data that RSP=j×TX−(smallest value among the tones TX to TZ), GSP=j×TY−(smallest value among the tones TX to TZ), BSP=j×TZ−(smallest value among the tones TX to TZ), and WSP=smallest value among the tones TX to TZ (where 1≦j≦2).
For example, in a case where it is specified in the RGB data that RSP=0, GSP=0, and BSP=0, it is specified in the RGBW data that RSP=1×0−(0)=0, GSP=1×0−(0)=0, BSP=1×0−(0)=0, and WSP=0. Alternatively, in a case where it is specified in the RGB data that RSP=255, GSP=255, and BSP=0, it is specified in the RGBW data that RSP=1×255−(0)=255, GSP=1×255−(0)=255, BSP=1×0−(0)=0, and WSP=0. Alternatively, in a case where it is specified in the RGB data that RSP=0, GSP=255, and BSP=255, it is specified in the RGBW data that RSP=1×0−(0)=0, GSP=1×255−(0)=255, BSP=1×255−(0)=255, and WSP=0.